Final answer:
Sympathetic preganglionic fibers are short and myelinated as they project to sympathetic ganglia close to the vertebral column. The correct answer is (b) short in length and myelinated.
Step-by-step explanation:
The sympathetic preganglionic fibers are characterized as being short in length and myelinated. This is because they are axons from the central neuron that project to a sympathetic ganglion, which is located close to the vertebral column. Therefore, the correct answer to the student's question is b) short in length and myelinated.
It's important to note that these preganglionic sympathetic fibers contrast with the postganglionic sympathetic fibers, which are long and unmyelinated due to the greater distance they cover from the ganglion to the target effector. On the other hand, the preganglionic parasympathetic fibers are typically longer as they travel to the terminal ganglia that are located near or within the target organs, and the postganglionic parasympathetic fibers are shorter.